

A296715


a(n) = [x^n] 1/Sum_{k=0..n} k^k*x^k.


5



1, 1, 3, 20, 197, 2511, 38924, 708105, 14769175, 347328540, 9093250277, 262350229095, 8271756463988, 283017783855881, 10445207569804687, 413662097635230500, 17499340294430480565, 787591765696468470799, 37578217833375886576604
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OFFSET

0,3


COMMENTS

A function f:[n]>[n] is decomposable if for some k < n, f([k]) is contained in [k] and f([nk]) is contained in [nk]. For n>=1, a(n) is the number of functions f:[n]>[n] that are not decomposable.  Geoffrey Critzer, Oct 16 2018


LINKS

Seiichi Manyama, Table of n, a(n) for n = 0..386


FORMULA

a(0) = 1; a(n) = Sum_{k=1..n} k^k * a(nk).  Ilya Gutkovskiy, Feb 07 2020


PROG

(PARI) N=66; x='x+O('x^N); Vec(1/sum(k=0, N, k^k*x^k))


CROSSREFS

Cf. A000312, A167894, A296617, A316090.
Sequence in context: A120485 A087152 A158833 * A054361 A052595 A244491
Adjacent sequences: A296712 A296713 A296714 * A296716 A296717 A296718


KEYWORD

sign


AUTHOR

Seiichi Manyama, Dec 19 2017


STATUS

approved



